Center locater



Feb. 12, 1957 B, E, PUCKETT 2,780,874

CENTER LOCATER Filed 0012. 30, 1956 A TTORNE YS inited StatCS This 'invention relates to a device for locating the center of ya cylindrical object. More particularly, the invention concerns a locating device for determining the position of the center of a cylindrical piece of metal bar stock, preparatory `to machining Ithe stock.

It is 1an object of this invention Ito provide -a device for assisting the operator of a lathe in mounting a shaft or the like between centers of the lathe, preparatory to machining the shaft. Although the prior art has suggested a variety of complicated and expensive machines for locating the center of such a shaft, it is a particular object of this invention to provide Aa low-cost, simple device which is economical to `operate `and to maintain, for accomplishing this purpose.

Before shafts or other cylindrical metal objects can be mounted between centers, it is necessary to locate the central axis of the shaft exactly, and to drill a conic-al recess at each end. In accordance with present practice, the machinist mounts one end of the shaft onto the headstock chuck, which may vbe a four-jaw independent chuck, for example. In this manner, the machinist centers that end of the shaft. The central portion of the shaft is then held steady by -a steady-rest, and if power is applied to the lathe the shaft rotates on centen A drill- -bit is then mounted in the tail-'stock of the lathe, and the drill-bit is fed into the rotating shaft to provide a recess of the desired depth. The bit is then removed from the tail-stock, a center is inserted into the tailstock, and the center and tail-stock. are brought up lagainst the shaft `so that the center tits into the recess in the shaft, after which the shaft is ready 'to be machined. This rather laborious process consumes considerable time, and ii is an object of this invention to provide a means for locating the centers accurately in much less time.

Other objects and advantages of this invention will further become apparent hereinafter, Vand in the drawings of which:

Fig. 1 represents a plan view of a center locater constructed in accordance with the principles of this invention, shown as applied to the end of a cylindrical object;

Fig. 2 represents a sectional View of the center locater and object, taken `as indicated by the lines and arrows II-II which Iappear in Fig. l; and

Fig. 3 represents a sectional view taken as indicated by the lines and arrows Ill- III which appear in Fig. l.

Referring now to the specific form of the invention as illustrated in the drawings, it is to be appreciated that the invention is not limited in scope to the specific form there shown, which is merely representative of one preferred manner in which the invention may 'be practiced. The number designates comprehensively an arm member which is frictionally slida-bly -connected to another arm member 11, as will appear in further detail hereinafter. The arm member 10 has a pair of parallel fingers i2 and 13. Finger 12 is pivoted at pin 14 to hinge plates 15, which are fixed to finger 13. Above the hinge 14, fingers 12, 13 are recessed at 16 providing =a recessed area for a spring 17 which is compression. Spring 1'7 urges the upper ends of the lingers 12, 13 aw-ay from one another,

2,780,874 Patented Feb. l2, 1957 therefore urging the free ends 20, 21 together. Intermediate the free ends of `the fingers 12, 13 they are provided with an elongated `slot 22 which extends parallel to the fingers for a substantial part of their length. Preferably, the upper inner edges 1S, 19 of the fingers 12, 13 are upwardly outwardly inclined.

The arm member 11 is simil-ar to the arm member 10 in the respects just described, but one linger l2 of the arm member l() has a side Wall 23 `slotted at 24 (see particularly Fig. 3), through which the other arm member 11 extends. Additionally, the slot 22 between the fingers 12' and 13 is wider than the slot 22, for a reason which will become apparent hereinafter.

The width of the slot 24 is substantially equal to thickness of the fingers of the arm member 1l, and provides frictional sliding Contact between the lingers of `the arm members 1li, 11, so that they may be adjusted lslidably at random with respect to one another. One linger 13 of the larm member 11 carries `a pin 25 which extends upwardly and can engage the wall 23, thereby preventing the separation of the yarm member l1 from the arm member 1li.

Each finger 12, 13 of the arm member di has a pin 26 which is arranged to contact the outer cylindrical surface of the shaft S lwhich is to be machined. The pins 26, 26 Iare spaced equally from the ends Ztl, 21 of the fingers. A line `drawn through the centers of pins 26, 26 is exactly perpendicular `to the axis of groove 22. Similarly, the fingers of the arm member 11 have fixed pin members 27, 27 which are equally spaced from the ends of the fingers and which are arranged to contact the outer surface of the shaft S. A line drawn ythrough the center of pins 27, 27 is exactly perpendicular to the axis of groove 22. When the arm members 1d, 11 are arranged at a substantial angle with respect to each other, as shown in Fig. l, with all four pins 26, 2o, 27, 27' in contact with the surface of the shaft S, their central slotted portions intersect with one another at `the center of the shaft, since any `two lines drawn perpendicular to tangents must intersect at the center of the circle. t will lbe observed that the grooves `along the centers of the arm members iti, 11 are of such width that they define a rectangular space into which the center-punch l may be placed. When the center-punch P is forced into the shaft S 'by means Vof a hammer blow, the lingers 12, i3, l2 and i3 are allowed to spring away from cach other in response to the blow, so that the` will not be destroyed by the punch P as it enters the metal. Since slot 22 is wider than slot 22, the conical surface of the end of punch P fits against the edges of all four fingers l2, i3, 12. 13', steadying and centering the punch.

Preferably, but not necessarily, a plurality' of parallel lines L are scribed on the surfaces of the fingers, to facilitate arranging the respective arm member perpendicular to each other.

The apparatus in accordance with this invention is extremely simple to use, since the operat-ors left hand may easily maneuver the arm members 1f?, 3'?. into place and also hold the center-punch P steady, while the righ*L hand applies a hammer blow to the end of "the punch.

Although the members 25 and 27 have 'been referred lo herein as pins, this expression is not intended to limit this invention to the use of cylindrical pins, since pins or protuberances of various shapes may readily be used.

It will be appreciated that the center locater in accordance with this invention maybe applied to shafts of widely varying diameters, from extremely small shafts up to very large ones, without sacrificing accuracy or ease in the use of the device. lt will further be understood that the center locator of this invention may easily be massproduced at low cost, that it is simple to operate, and that it requires little or no maintenance. Additionally, it is readily portable and requires very little storage space.

While this invention has been described with reference to one embodiment thereof, it will be apparent to `those skilled in the art that various changes other than those referred to above may be made in the form of the device, that equivalent elements may be substituted for those illustrated in the drawings, that parts may be reversed, and that certain features of the invention may be used to advantage independently of the use of other features, all within `the spirit of the invention as defined in the appended claims.

Having thus described my invention, I claim:

l. A device for locating the center of -a generally cylindrical object comprising a pair of relatively moveable arm members located in adjacent, parallel planes and slidably cngageable with one another, each of said arm members comprising a pair of fingers pivoted to one another with an elongated slot therebetween, pins carried by the respective lingers and arranged along a line perpendicular to the axis of said elongated slot, and resilient means connected between said ngers continuously urging the free ends of said fingers, `at the end of said slot, toward one another. j

2. The device defined in claim l, wherein a nger of one of said arm members has an upstanding slotted side wall member, and wherein the other of said arm members extends through said slot.

3. The device defined in claim 2, wherein said other arm member includes a stop member located outwardly of said slotted side wall member, preventing separation of the arm members from one another.

4. The device defined in claim 2, wherein the slot in said side wall member has a width substantially equal *to the thickness of the lingers of the other arm member, said wall frictionally engaging said lingers.

5. The device dened in claim l, wherein one of said `arm members is -on top of the other, and wherein the slot of the lower arm member is narrower than the slot of the upper arm member.

6. The device delined in claim 5, wherein the upper inner edge of each of said lingers adjacent said grooves, is upwardly outwardly inclined.

7. The device dened in claim 1, wherein said `resilient means comprises a compression spring contacting both of said fingers ata location adjacent their pivotal connection.

8. The device defined in claim 7, wherein each of said fingers is cut -away adjacent said pivotal connection, providing a recess in which said compression spring is housed.

No references cited. 

